Kethobile Elias, Ketlogetswe Clever, Gandure Jerekias
Department of Mechanical Engineering, Faculty of Engineering and Technology, University of Botswana, Gaborone, Botswana.
Department of Agricultural Research, Ministry of Agricultural Development and Food Security, Botswana.
Heliyon. 2020 Dec 9;6(12):e05657. doi: 10.1016/j.heliyon.2020.e05657. eCollection 2020 Dec.
The use of non-oil biomass in the energy mix as a solid fuel offers the most effective ways of utilising such resource. However, available information indicates that biomass has negative inherent properties which lower its fuel value. This negative effect can be improved by slow pyrolysis process called torrefaction where the biomass is heated in the range of 200 °C to 300 °C. In the present investigation the effects of torrefaction temperature on the solid fuel value of different biomass materials were determined. Consequently, three types of biomass namely; seed cake, stem and fruit cover were considered under five temperature levels (200 °C, 225 °C, 250 °C, 275 °C, 300 °C). Analysis of Variance (ANOVA) revealed that there were significant differences (P > 0.05) in bulk density, hygroscopicity, energy content and ultimate etc. The statistical analysis results indicated that there was biomass type and torrefaction temperature interaction effects on the ultimate analysis, bulk density, hygroscopicity, energy content and energy yield. The interaction effects of the factors under investigation were not observed in mass yield. Increase in torrefaction temperature generally reduced the equilibrium moisture content and volatile matters across the biomass types. However fixed carbon, carbon content, ash content and energy density were increased across the biomass types as the temperature was increased from 200 °C to 300 °C. The torrefied seed cake biomass showed relatively enhanced fuel characteristics than the torrefied stem and the torrefied fruit husk when considering the properties under investigation.
在能源结构中使用非油生物质作为固体燃料是利用此类资源的最有效方式。然而，现有信息表明生物质具有负面固有特性，会降低其燃料价值。通过一种称为烘焙的缓慢热解过程可以改善这种负面影响，即在200℃至300℃的范围内加热生物质。在本研究中，确定了烘焙温度对不同生物质材料固体燃料价值的影响。因此，考虑了三种生物质，即籽饼、茎和果壳，在五个温度水平（200℃、225℃、250℃、275℃、300℃）下进行研究。方差分析（ANOVA）表明，在堆积密度、吸湿性、能量含量和元素分析等方面存在显著差异（P>0.05）。统计分析结果表明，生物质类型和烘焙温度对元素分析、堆积密度、吸湿性、能量含量和能量产率存在交互作用。在所研究的因素中，未观察到质量产率的交互作用。一般来说，随着烘焙温度的升高，所有生物质类型的平衡水分含量和挥发性物质都会降低。然而，当温度从200℃升高到300℃时，所有生物质类型的固定碳、碳含量、灰分含量和能量密度都会增加。考虑到所研究的特性，烘焙后的籽饼生物质比烘焙后的茎和烘焙后的果壳表现出相对增强的燃料特性。
